Experts say western Colorado has 40 times more natural gas than previously thought, potentially making it the second-largest formation in the country.
But they say an immediate boom is unlikely because prices are too low.
The U.S. Geological Survey said that Colorado's Piceance Basin formation holds about 66 trillion cubic feet of gas, up from 1.6 trillion estimated in 2003.
USGS cited new research for the revision.
David Ludlam of the West Slope Colorado Oil and Gas Association says prices are too low to spur a boom. But he says that when prices rise, well sites and pipelines are in place from previous drilling in a shallower formation.
Ludlam says the Piceance would be second only to the Marcellus formation in the eastern U.S. The Marcellus has 84 trillion cubic feet of gas.